1. Field of the Invention:
The present invention relates to a sealing apparatus for sealing a liquid, such as an oil. More particularly, the invention pertains to a sealing apparatus which has a main lip and is arranged such that, when a shaft is inserted into the seal apparatus, the main lip is prevented from being inverted by the inserted shaft.
2. Description of the Prior Art:
As a prior art relating to the present invention, there is a sealing apparatus such as that shown in FIG. 4. FIG. 4 is a sectional view of the conventional sealing apparatus. The sealing apparatus is composed of: an outer peripheral portion 101 which is fitted to the inner peripheral surface of a housing 100; a radial portion 102 which extends radially inward from one of the ends of the outer peripheral portion 101; a seal lip 103 which extends axially obliquely from the inner end of the radial portion 102; and a reinforcing metal ring 104 with a substantially L-shaped cross-section which is disposed such as to stretch from the inner peripheral surface of the outer peripheral portion 101 to one of the side surfaces of the radial portion 102. A seal portion 105 of a substantially V-shaped cross-section is integrally formed at the distal end of the seal lip 103. The seal portion 105 is formed such as to possess an inside diameter which is smaller than the outside diameter of a shaft 106 in order to offer a satisfactory sealing effect. For this reason, when the shaft 106 is inserted into the sealing apparatus from the side thereof which is closer to the seal portion 105 of the seal lip 103 as shown in FIG. 4, the seal lip 103 is undesirably bent by the shaft 106 in the advancing direction of the shaft 106, so that the sealing apparatus is unfavorably mounted in the state wherein the seal portion 105 is not in close contact with the shaft 106. In the case where a gutter spring 107 is fitted on the outer periphery of the seal lip 103, when the seal lip 103 is bent by the inserted shaft 106, the gutter spring 107 undesirably comes off the seal lip 103, so that the sealing apparatus is inconveniently mounted with the gutter spring 107 separated from the seal lip 103. FIG. 5 shows another example of the conventional sealing apparatus. This conventional sealing apparatus is mounted in the state wherein the seal lip 103 is undesirably bent by the inserted shaft 106. In consequence, it is not possible to expect the sealing apparatus to offer a proper shaft-sealing effect. It is to be noted that the same members or portions in FIG. 5 as those in FIG. 4 are denoted by the same reference numerals.